1. Field of the Invention
The invention relates generally to electrical connector assemblies and more particularly to a twist lock housing and face plate attachment for electrical connector assemblies of the conventional two and three prong type for preventing inadvertent separation of two mating connector ends when plugged together or inadvertent disconnection of a single male connector plug end from a receiving wall socket.
2. Brief Description of the Prior Art
In the area of electrical plug connectors, such as for example, the common two-prong or three-prong type electrical plug connectors, it is desirable to ensure that the male plug end remains connected to the female receiving socket end of an extension cord or to a receiving wall socket during use. From U.S. Pat. No. 3,891,289 issued to Hanke, a lockable electrical outlet is described wherein the electrical outlet is provided with a rotatable locking pin having a camming surface thereon and which is operative to individually close a pair of electrical contact assemblies to ensure a positive engagement with the corresponding blade contacts of an inserted male plug assembly.
A disadvantage with the rotatable locking pin arrangement of Hanke is that a finger-actuated lever portion of the rotatable locking pin member protrudes outwardly from the electrical outlet housing and, thus exposed, the lever tends to snag or hang up on fixtures or other immobile objects during use. This becomes a major inconvenience, such as for example, when a user of a power tool yanks or pulls on the extension cord and the connector assembly becomes stuck on some fixture. A stuck connector assembly means that the user must stop work and go to the site of the plug connector hang up and fix the obstruction problem. Otherwise, continued pulling on the cord may inadvertently move the exposed lever to the open position thus releasing the plug from engagement; here again, requiring the user to stop work and go to the problem area to reconnect the connector assembly and adjust the cord in an attempt to avoid further entanglements.
In the construction industry, use of extension cords for connecting power tools to a power source is wide spread. Also, the nature of the work may require moving the extension cord several times during a job, thus giving rise to the possibility that the cord will snag on stationary objects or fixtures.
Inadvertent disconnection of extension cords account for a majority of interruptions on the job. Also, locking designs of prior art electrical connectors of the type described above have not proved popular in view of the added costs and complexity associated with parts and labor in manufacture of the female socket end.
Accordingly, there is a definite need in the art for an improved low cost electrical plug locking assembly which may be implemented in an extension cord or a wall mounted outlet and which overcomes the problems of the prior art.